It has been recognised in the beer brewing industry that the production of wort in a continuous operation offers a number of advantages, including:                higher productivity and lower investment: vessels can be operated for prolonged periods of time under full load, meaning that for equal production volume smaller vessels are needed than in a batch process;        constant and better quality: process is easier to control due to possibility of adapting process parameters to local and instantaneous requirements and because steady-state-conditions are much more stable;        high hygienic standard: continuous process is operated in a closed system.        less energy: energy consumption is evenly spread, without major use peaks;        less labour: operation of continuous process requires less attention        less standstill and cleaning: continuous process can be operated at much longer runlengths than batch processes.        
Many efforts have been made since the end of the 19th century to realise one or more of the above advantages through the development of continuous brewing processes. However, to date across the globe not more than just a couple of breweries have actually introduced continuous brewing operations such as continuous wort production and/or continuous fermentation into their factories.
In the prior art beer brewing processes have been described that comprise the preparation of a high gravity mash extract. U.S. Pat. No. 4,140,799 describes a batch process for the preparation of an alcoholic beverage, comprising the steps of preparing an aqueous fermentable substrate containing fermentable carbohydrates and having a solids content in the range of 18° to 36° Plato. It is stated in the US patent that, in general, the wort is prepared by mashing malt with an adjunct, with the malt comprising from about 35% to 65% by weight of the total extract weight. The US patent teaches to reduce the solids content by dilution as soon as carbohydrate consumption rate during fermentation decreases as signified by foam collapse.
U.S. Pat. No. 4,371,550 describes a batch process for beer brewing which comprises mixing a high-gravity fermenting liquor comprising a fermenting wort of an original gravity of 14-21° P, which has passed through the high krausen period, and a low gravity liquor comprising a fermenting wort or wort of an original gravity of 3-6° P and subjecting the resulting mixture to fermentation to obtain a beer of an original gravity of 6-9° P. The process described in this US patent is said to be particularly suitable for the production of light beer, i.e. beer of low original gravity.
U.S. Pat. No. 4,397,872 describes a batch method of brewing beer wherein wort is produced from a mash consisting essentially of water, malt, and a substantial amount of rice as an adjunct, the improvement comprising using as said rice strains of rice having a gel point of 70° C. or less, and using increased amounts of malt and rice in direct proportions in the mash to obtain a wort having a cold wort concentration of 16° Balling or higher to produce a high gravity beer. In the US patent it is observed that a degree of Balling means a percent solids in the wort.
DE-A 44 01 694 describes a batch process for the preparation of filtered wort that uses recovered filter water to achieve enhanced concentration of the wort. The stated aim is to arrange the separation process with the mash filter in such a way that a final concentration, prior to concentration by evaporation, of more than 19 GG-% is achieved. Furthermore, it is observed in the German patent application that preferably the primary wort concentration is between 23 GG-% and 25 GG-%.
The above prior art publications do not disclose a continuous brewing process comprising the preparation and further processing of a high gravity mash extract into a high gravity wort. Furthermore, the aforementioned publications rely on the addition of high levels of adjuncts after starch hydrolysis (mash heating) to prepare high gravity mash extract.